Mars Dust Fine Enough to Reach the Lungs Is Clinging to Spacesuit Samples
NASA said its Perseverance rover has measured the size of fine and ultrafine Martian dust grains clinging to swatches of real spacesuit material carried aboard it, over 1,645 Martian days. The agency calls these the first on-site measurements of fine and ultrafine particles on Mars. The paper was published Oct. 27, 2026, in the Proceedings of the National Academy of Sciences.
In its release on the work, the agency says the sizes could inform spacesuit and habitat design, dust-removal procedures and crew health standards for future Mars missions. The study also found that some materials hold less dust than others, which the agency says could guide later choices of materials and coatings for suits and habitats.
The dust was sized by PIXL, an X-ray spectrometer on the rover's arm. One patch of the plate PIXL uses to check its settings is Teflon, which holds no element the instrument can see, so every signal off it comes from dust. The fine particles measured less than 2.5 micrometers across and the ultrafine ones around 100 nanometers. A human hair is about 70 micrometers wide. Earlier work on Mars had resolved grains only down to about 3 micrometers.
Static electricity appears to decide which sizes stick to which surface, and the finest grains stayed attached through years of driving and drilling. "The larger clumps, the Martian dust bunnies, get shaken off over time. But the smallest particles stay behind, and those are the ones that pose the greatest challenge for human support systems," said Scott VanBommel of Washington University in St. Louis, the paper's lead author.
On Earth, particles that small are linked to health effects because they can reach deep into the lungs and the bloodstream. NASA's account says scientists believe the risk from Mars dust depends on how much of it there is and how long the exposure lasts.
PIXL also found the dust enriched in phosphorus, with signs of calcium sulfate, in an iron- and sulfur-rich mix matching what earlier missions measured.
